The
carnivorous pitcher plant Nepenthes bicalcarata isn't that terrifying
of a deathtrap: its pitcher leaf isn't slippery and it doesn't have
the corrosive slime that kill its victims quickly.

But it does have something that makes up for all those weaknesses: vicious
bodyguard ants!

The carnivorous plant has swollen tendrils at the base of each
pitcher that serve as homes for the insects, and a food source in the
form of nectar secreted on the pitcher rims.

In return, the ants apparently provide a host of services for the
pitcher plants. They clean the pitcher mouth to keep it slippery enough
to help catch prey. They attack weevils that would otherwise munch on
the plant. They cart off the remains of large prey from the pitchers
that would otherwise rot. They lie in ambush under pitcher rims and
systematically attack any of the plant's prey that attempt to escape
the traps. And their droppings fertilize the plants.